[frostfire]

Just wondering if any of the people from Australia could clear something up for me....

I read that Australian scientist have discovered a contraceptive pill for kangaroos, as the number of kangaroos is causing chaos for the locals.
I found it quite suprising that native species were actually causing problems because there are too many. Usually you only hear that non-native species, that have been released into the wild, do that. I was just wondering what problems they were causing, that people are trying to find ways to decrease their numbers, as 99.99% of the time we are trying to find ways of keeping species from extinction.
Apparently on Kangaroo Island a same type of pill was used to keep koala numbers down. Something else that suprised me, as I thought koalas were endangered species.
The article wasn't very informative really, so can anyone explain more?